Magento2: Assign products to category programatically

Question

I want to assign product problematically to category. Magento\Catalog\Api\CategoryLinkManagementInterface using DI. below is snippet of code.

    protected $categoryLinkManagement;

    public function __construct(
    \Magento\Framework\Stdlib\DateTime\Timezone $_stdTimezone,
    \Magento\Framework\Stdlib\DateTime\DateTime $stdlibDateTime,
    \Kensium\Newproduct\Model\CategoryLink $categoryLinkManagement,
    \Magento\Backend\Block\Template\Context $context,
    \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
    array $data = []
    ) {
        $this->_stdTimezone = $_stdTimezone;
        $this->stdlibDateTime = $stdlibDateTime;
        $this->categoryLinkManagement = $categoryLinkManagement;
        $this->_productCollectionFactory = $productCollectionFactory;
        parent::__construct($context, $data);
    }

    /**
     * Method executed when cron runs in server
     */
    public function execute() {
    $pid = array();

    $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
    $newCategoryId = $objectManager->create('\Magento\Framework\App\Config\ScopeConfigInterface')->getValue('productlabels/newtodays/newcategoryid');
$saleCategoryId = $objectManager->create('\Magento\Framework\App\Config\ScopeConfigInterface')->getValue('productlabels/newtodays/salecategoryid');

    $collection = $this->_productCollectionFactory->create();
    $this->NewProducts($collection,$newCategoryId);
    $this->SaleProducts($collection,$saleCategoryId);


    }

    private function getCategoryLinkManagement()
    {
        if (null === $this->categoryLinkManagement) {
        $this->categoryLinkManagement = \Magento\Framework\App\ObjectManager::getInstance()
            ->get('\Kensium\Newproduct\Model\CategoryLink');
        }
        return $this->categoryLinkManagement;
    }
public function NewProducts($collection,$newCategoryId)
        {
        $today = $this->_stdTimezone->date()->format('Y-m-d H:i:s');
        $lastday = date('Y-m-d h:m:s', strtotime($today."+90 days"));
            $collection->addAttributeToSelect('*')             
                   ->addFieldToFilter('new_to', ['lteq' => $lastday]);

        foreach($collection as $col):
            if($col->getSku()):
                $this->getCategoryLinkManagement()->assignProductToCategories(
                    $col->getSku(),
                    array($newCategoryId)
                );


            endif;
        endforeach;
        }

This work when product is assign to another category. but there is 2 problem

1)Product should assign to other category otherwise i will get error category doesn't contain product due to below code in

$this->getCategoryLinkRepository()->deleteByIds($categoryId, $productSku);

on Magento\Catalog\Model\CategoryLinkManagement :: assignProductToCategories()

2) This will remove product from other categories.

Is there any other option to achieve this?

Answer 1

You can find the following code , It will assign product to the category

     protected $productLinkFactory;

     /**
     * @var \Magento\Catalog\Api\CategoryLinkRepositoryInterface
     */
    protected $categoryLinkRepository;

       public function __construct( 
      \Magento\Catalog\Api\Data\CategoryProductLinkInterfaceFactory 
      $productLinkFactory)
      {
        $this->productLinkFactory = $productLinkFactory;
      }

   public function assignProduct()
   {
     $sku=234;
     $categoryId=23;
    $this-> getCategoryLinkManagement($sku, $categoryId);
   }

   public function getCategoryLinkManagement($sku, $categoryId)
    {

        $categoryProductLink = $this->productLinkFactory->create();
        $categoryProductLink->setSku($sku);
        $categoryProductLink->setCategoryId($categoryId);
        $categoryProductLink->setPosition(0);
        $this->getCategoryLinkRepository()->save($categoryProductLink);

        return true;


    }


    private function getCategoryLinkRepository()
    {
        if (null === $this->categoryLinkRepository) {
            $this->categoryLinkRepository = \Magento\Framework\App\ObjectManager::getInstance()
                ->get(\Magento\Catalog\Api\CategoryLinkRepositoryInterface::class);
        }
        return $this->categoryLinkRepository;
    }